The subject matter disclosed herein relates to X-ray imaging and, in particular, to the fabrication and use of a tiled radiation detector as a radiological imaging unit consisting of an X-ray image intensifier and a CCD (charge-coupled device) camera. For the sake of simplicity, the term image intensifier, when used herein, refers to the entire radiological imaging unit.
Non-invasive imaging technologies allow images of the internal structures or features of a patient or object to be obtained without performing an invasive procedure on the patient or object. In particular, such non-invasive imaging technologies rely on various physical principles, such as the differential transmission of X-rays through the target volume or the reflection of acoustic waves, to acquire data and to construct images or otherwise represent the observed internal features of the patient or object.
For example, in fluoroscopy and other X-ray based imaging technologies, X-ray radiation is directed toward a subject, typically a patient in a medical diagnostic application, a package or baggage in a security screening application, or a fabricated component in an industrial quality control or inspection application. A portion of the radiation impacts a detector where the image data is collected and used in an image generation process. In the images produced by such systems, it may be possible to identify and examine the internal structures and organs within a patient's body, objects within a package or container, or defects (e.g., cracks) within a fabricated component. In certain contexts, such as fluoroscopy applications used in support of interventional or navigation procedures, low-dose X-rays may be acquired at a high frame rate over an extended period to provide real-time image data that may be used to guide or navigate a tool within a patient.
In the context of fluoroscopy, an image intensifier is conventionally used to detect the transmitted X-rays and to generate useful signals for image generation. Such conventional image intensifiers are generally provided as bulky, cylindrical devices having either a 6″, 9″ or 12″ diameter active area. The image intensifier converts X-rays to images often in substantially real time.
One obstacle to replacing image intensifiers in legacy systems with newer radiation detector technology is the form factor of the image intensifiers in the installed base of devices. In particular, in existing fluoroscopic installations, the image intensifiers are typically provided as cylindrical components, and thus have a round cross section. In contrast, flat panel X-ray detectors are conventionally square or rectangular in form factor which corresponds to the row-column matrix readout of the pixel arrays. Thus, replacing the existing circular cross-section image intensifiers with square or rectangular flat panel detectors is not a straight-forward operation if it is desired to maintain the existing cylindrical form factor.